U.S. patent application number 10/058063 was filed with the patent office on 2002-10-24 for method of manufacturing honeycomb extrusion die and die manufactured according to this method.
This patent application is currently assigned to NGK Insulators, Ltd.. Invention is credited to Asai, Yuji, Furutani, Makoto, Matsumoto, Keiji.
Application Number | 20020152603 10/058063 |
Document ID | / |
Family ID | 18885539 |
Filed Date | 2002-10-24 |
United States Patent
Application |
20020152603 |
Kind Code |
A1 |
Asai, Yuji ; et al. |
October 24, 2002 |
Method of manufacturing honeycomb extrusion die and die
manufactured according to this method
Abstract
A method of manufacturing a honeycomb extrusion die has the
steps of: preparing a die base metal in which a plurality of
intersecting slits are arranged in a front surface thereof and a
plurality of raw material feeding holes communicated with the slits
are arranged in a back surface thereof; forming a plating layer on
the die base metal by means of electrolytic plating; (1) and
forming a TiCN layer on the plating layer by means of CVD (chemical
vapor deposition); or (2) forming a TiN layer on the plating layer
by means of CVD (chemical vapor deposition); and forming a TiCN
layer on the TiN layer by means of CVD. In this manner, the
honeycomb extrusion die is obtained.
Inventors: |
Asai, Yuji; (Nagoya City,
JP) ; Furutani, Makoto; (Komaki City, JP) ;
Matsumoto, Keiji; (Nagoya City, JP) |
Correspondence
Address: |
PARKHURST & WENDEL, L.L.P.
1421 PRINCE STREET
SUITE 210
ALEXANDRIA
VA
22314-2805
US
|
Assignee: |
NGK Insulators, Ltd.
Nagoya City
JP
|
Family ID: |
18885539 |
Appl. No.: |
10/058063 |
Filed: |
January 29, 2002 |
Current U.S.
Class: |
29/527.2 |
Current CPC
Class: |
Y10T 428/12361 20150115;
B28B 7/346 20130101; C23C 16/0281 20130101; Y10T 29/49982 20150115;
C25D 7/00 20130101; Y10T 428/12 20150115; C23C 28/04 20130101; B28B
3/269 20130101 |
Class at
Publication: |
29/527.2 |
International
Class: |
B23P 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 2001 |
JP |
2001-19,702 |
Claims
What is claimed is:
1. A method of manufacturing a honeycomb extrusion die comprising
the steps of: preparing a die base metal in which a plurality of
intersecting slits are arranged in a front surface thereof and a
plurality of raw material feeding holes communicated with the slits
are arranged in a back surface thereof; forming a plating layer on
the die base metal by means of electrolytic plating; and forming a
TiCN layer on the plating layer by means of CVD (chemical vapor
deposition).
2. A method of manufacturing a honeycomb extrusion die comprising
the steps of: preparing a die base metal in which a plurality of
intersecting slits are arranged in a front surface thereof and a
plurality of raw material feeding holes communicated with the slits
are arranged in a back surface thereof; forming a plating layer on
the die base metal by means of electrolytic plating; forming a TiN
layer on the plating layer by means of CVD (chemical vapor
deposition); and forming a TiCN layer on the TiN layer by means of
CVD.
3. The method of manufacturing a honeycomb extrusion die according
to claim 1 or 2, wherein the plating layer is made of Ni, Co, Cu or
transition metals which are not easily nitrided or oxidized.
4. The method of manufacturing a honeycomb extrusion die according
to claim 1 or 2, wherein a thickness of the plating layer is more
than 0.01 .mu.m.
5. A die manufactured according to the method of manufacturing a
honeycomb extrusion die set forth in claim 1, comprising: a die
base metal having slits and raw material feeding holes; a plating
layer formed on the die base metal; and a TiCN layer formed on the
plating layer.
6. A die manufactured according to the method of manufacturing a
honeycomb extrusion die set forth in claim 2, comprising: a die
base metal having slits and raw material feeding holes; a plating
layer formed on the die base metal; a TiN layer formed on the
plating layer; and a TiCN layer formed on the TiN layer.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a method of manufacturing a
honeycomb extrusion die used for extruding a ceramic honeycomb
structural body and a honeycomb extrusion die manufactured
according to this method.
[0003] (2) Prior Art Statement
[0004] Generally, as a die for extruding a ceramic honeycomb
structural body, a honeycomb extrusion die is known in which a
plurality of intersecting slits are arranged in a front surface of
a die base metal and a plurality of raw material feeding holes
communicated with the slits are arranged in a back surface of the
die base metal. In such a honeycomb extrusion die, in order to
improve a wear resistance of the slits, there is disclosed a
technique in JP-A-60-145804 in which at least a part of the die
base metals defining the slits is formed by coating iron boride,
chromium carbide, aluminum oxide, titanium carbide, titanium
nitride or titanium nitride carbide by means of CVD (chemical vapor
deposition).
[0005] However, in the case that a TiN layer and a TiCN layer are
to be formed successively on the die base metal made of for example
martensite stainless steel by utilizing the CVD technique, it is
known that, if a thickness of the TiN layer or the TiCN layer
becomes thicker, a chipping (film peeling off after film formed) is
easily generated. This chipping is easily generated particularly at
round (R) portions formed by rounding corner portions of the die
base metal defining the slits. If the chipping is generated, a
coating defect occurs. Therefore, there is a problem such that a
productivity of the ceramic honeycomb structural body becomes
worse.
[0006] On the contrary, the applicant discloses a technique not for
eliminating the chipping generation but for narrowing a slit width
of the die base metal, in JP-A-10-309713, such that an electroless
plating layer made of for example Ni is formed on the die base
metal and the TiCN layer and a W.sub.2C layer is formed on the
electroless plating layer by means of CVD. However, if this
technique is utilized for eliminating the chipping generation,
there occurs following problems. That is, P is included in the
electroless plating layer made of for example Ni as an impurity.
Therefore, if the TiN layer and the TiCN layer are formed on the
electroless Ni-P plating layer by CVD, the plating layer and the
CVD layer are reacted and it is not possible to obtain normal TiCN
particles.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to eliminate the
drawbacks mentioned above and to provide a method of manufacturing
a honeycomb extrusion die and a die according to this method in
which a coating layer with no chipping can be formed on a die base
metal and a productivity of a ceramic honeycomb structural body
during an extrusion operation can be improved.
[0008] According to a first aspect of the invention, a method of
manufacturing a honeycomb extrusion die comprises the steps of:
preparing a die base metal in which a plurality of intersecting
slits are arranged in a front surface thereof and a plurality of
raw material feeding holes communicated with the slits are arranged
in a back surface thereof; forming a plating layer on the die base
metal by means of electrolytic plating; and forming a TiCN layer on
the plating layer by means of CVD (chemical vapor deposition).
[0009] Moreover, according to a second aspect of the invention, a
method of manufacturing a honeycomb extrusion die comprises the
steps of: preparing a die base metal in which a plurality of
intersecting slits are arranged in a front surface thereof and a
plurality of raw material feeding holes communicated with the slits
are arranged in a back surface thereof; forming a plating layer on
the die base metal by means of electrolytic plating; forming a TiN
layer on the plating layer by means of CVD (chemical vapor
deposition); and forming a TiCN layer on the TiN layer by means of
CVD.
[0010] Further, according to the invention, a die manufactured
according to the first aspect of the second aspect of the method of
manufacturing the honeycomb extrusion die, comprises: (1) a die
base metal having slits and raw material feeding holes; a plating
layer formed on the die base metal; and a TiCN layer formed on the
plating layer, or, (2) a die base metal having slits and raw
material feeding holes; a plating layer formed on the die base
metal; a TiN layer formed on the plating layer; and a TiCN layer
formed on the TiN layer.
[0011] In the present invention, since the electrolytic plating
layer is arranged between the die base metal and the TiCN layer or
between the die base metal and the TiN layer, a contact property
therebetween can be improved, so that the chipping is not easily
generated if a thickness of the film is thicker. Moreover, since
the plating layer is made of the metal and the metal has an
excellent stiffness, it is possible to reduce a heat stress between
the die base metal and the TiCN layer or the TiN layer, and thus
the chipping is not easily generated. Further, since an impurity in
the electrolytic plating layer is very little, it is possible to
obtain normal TiCN particles.
[0012] In the preferred embodiment of the method of manufacturing
the honeycomb extrusion die according to the invention, the plating
layer is made of Ni, Co, Cu or transition metals which are not
easily nitrided or oxidized, and a thickness of the plating layer
is not less than 0.01 .mu.m. In the both embodiments, it is
possible to achieve the present invention more effectively, and
thus they are preferred.
BRIEF DESCRIPTION OF THE DRAWING
[0013] For a better understanding of the present invention,
explanations are made to the following drawings wherein:
[0014] FIG. 1 is a flowchart for explaining a method of
manufacturing a honeycomb extrusion die according to the
invention;
[0015] FIGS. 2a and 2b are schematic views respectively showing one
embodiment of a honeycomb extrusion die according to the
invention;
[0016] FIG. 3 is a schematic view illustrating an enlarged part of
the honeycomb extrusion die according to the invention;
[0017] FIG. 4 is a SEM photograph depicting a cross section of the
die according to an example of the invention;
[0018] FIG. 5 is a SEM photograph showing a cross section of a die
according to a comparative example; and
[0019] FIG. 6 is a SEM photograph illustrating a chipping state in
the comparative example.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] FIG. 1 is a flowchart for explaining a method of
manufacturing a honeycomb extrusion die according to the invention.
According to the flowchart shown in FIG. 1, a first aspect and a
second aspect of a method of manufacturing a honeycomb extrusion
die according to the invention will be explained. At first, in the
both embodiments, a die base metal, in which a plurality of
intersecting slits are arranged in a front surface thereof and a
plurality of raw material feeding holes communicated with the slits
are arranged in a back surface thereof, is prepared (step 1). As a
material of the die base metal, use may be made of all the
materials that are conventionally used for the die base metal. For
example, a martensite stainless steel can be preferably used.
Moreover, workings of the slits and the raw material feeding holes
may be performed by conventional methods. For example, the slits
can be formed by EDM (Electro-discharged machining) process and/or
wheel grinding process. Further, the raw material feeding holes can
be formed by ECM (Electro-chemical machining) process.
[0021] Then, a plating layer is formed on the thus prepared die
base metal by means of electrolytic plating (step 2). As a material
of the plating layer, it is preferred to use Ni, Co or Cu and more
preferred to use transition metals that are not easily nitrided or
oxidized as compared with Fe or Cr. In this case, since Ni used for
electrolytic plating is a pure metal, it is possible to obtain
normal TiCN particles. However, since Ni contains a little amount
of Co as an impurity at a rate of {fraction (1/100)} of Ni, Ni is
not a pure metal but an alloy if strictly speaking. Moreover, as a
method of forming the plating layer made of Ni by means of
electrolytic plating, use may be made of the known methods such as
method of using a wood-strike bath, method of using a sulfamic acid
bath, method of using a watt bath and method of using an immersion
nickel bath. In the case that the plating layer made of metals
other than Ni is formed by means of electrolytic plating,
electrolytic plating operation can be performed in the
substantially same manner as that of Ni by using a bath of cobalt
chloride (CoCl.sub.2) solution in the case of Co and a bath of
copper sulfate (CuSO.sub.4) solution in the case of Cu. Further, in
the case that a film is directly formed on the die base metal by
means of CVD, a composition of the die base metal is limited (that
is, in accordance with a composition of the die base metal, the
film is formed normally in some cases but the film is not formed in
the other cases). However, in the case that the film is formed by
electrolytic plating, a composition of the die base metal is not
limited (that is, all the compositions of the die base metal are
used if only electrolytic plating can be performed on the die base
metal). Furthermore, a thickness of the electrolytic plating layer
is preferred to be not less than 0.01 .mu.m. If this thickness is
less than 0.01 .mu.m, nitriding and oxidizing of the die base metal
occur, and a contacting performance after forming the film is
decreased. Therefore, from a point of view of the contacting
performance, this thickness has no upper limit. However, an upper
limit of this thickness is determined on the basis of the other
conditions such as economical efficiency.
[0022] Then, in the first aspect of the invention, a TiCN layer is
formed on the electrolytic plating layer by means of CVD (step 3).
Moreover, in the second aspect of the invention, a TiN layer is
formed on the electrolytic plating layer by means of CVD (step 4),
and then a TiCN layer is formed on the TiN layer by means of CVD
(step 5). In the both embodiments, since the electrolytic plating
layer is arranged, it is possible to achieve an excellent
contacting performance with no chipping. In this case, since the
TiCN layer limits a material of the electrolytic plating layer by
means of CVD to achieve an excellent contacting performance, it is
easy to use the second aspect pf the invention using the TiN layer,
which does not limit a material of the electrolytic plating layer
by means of CVD as compared with the TiCN layer.
[0023] In the present invention mentioned above, it is possible to
improve a contacting performance between the die base metal and the
TiCN layer of between the die base metal and the TiN layer by
arranging the electrolytic plating layer between the die base metal
and the TiCN layer or between the die base metal and the TiN layer.
This reason is estimated as follows. That is, in the case that the
TiCN layer or the TiN layer is to be formed directly on the die
base metal made of stainless steel by means of CVD, since stainless
steel has a thin Cr oxide (a few nm) on its surface layer, a
contacting performance is reduced due to this Cr oxide. In
addition, in the case that the TiN layer and the TiCN layer are
formed, N.sub.2 (nitrogen) gas is flowed during a TiN layer forming
operation. In this case, a nitriding layer (CrN, FeN and so on) is
formed due to this N.sub.2 gas, and thus this nitriding layer
decreases its contacting strength. In the present invention, the
electrolytic plating layer made of for example Ni is formed on a
surface of the die base metal made of stainless steel, and the TiCN
layer or the TiN layer and the TiCN layer is (are) formed on the
electrolytic plating layer by means of CVD. Therefore, these
phenomena such as a nitriding layer generation do not occur, and
thus it is possible to improve the contacting performance between
the die base metal and the TiCN layer or between the die base metal
and the TiN layer. That is, since Ni is not easily oxidized or
nitrided as compared with Cr or Fe, the above advantage can be
obtained. Moreover, the transition metals other than Ni, which are
not easily nitrided or oxidized as compared with Co, Cu further Fe
or Cr, have also the same advantage.
[0024] Moreover, in the present invention mentioned above, since
the plating layer is made of a metal which shows an excellent
stiffness, it is possible to reduce a heat stress between the die
base metal and the TiCN layer or the TiN layer. For reference,
thermal expansion coefficients of TiCN, TiN, martensite stainless
steel, Ni and Co are shown in the following Table 1. As is clearly
understood from the thermal expansion coefficients shown in the
following Table 1, since, in the present invention, Ni or Co having
an intermediate thermal expansion coefficient between those of the
die base metal and the film is inserted between the die base metal
and the film, it is possible to reduce a heat stress. Moreover,
since Ni, Co and so on are a pure metal, they show an excellent
stiffness and thus it is possible to absorb a heat stress.
1 TABLE 1 Material Thermal expansion coefficient (/.degree. C.)
TiCN 8.1 .times. 10.sup.-6 TiN 9.3 .times. 10.sup.-6 Ni 16.5
.times. 10.sup.-6 Co 12.0 .times. 10.sup.-6 Martensite stainless
steel 19.5 .times. 10.sup.-6 (At descending temperature from film
forming temperature of near 800.degree. C. to room temperature)
[0025] FIG. 2 is a schematic view showing one embodiment of a
honeycomb extrusion die according to the invention, wherein FIG. 2a
illustrates its plan view and FIG. 2b depicts its cross sectional
view along A-A line. In the embodiment shown in FIGS. 2a and 2b, a
honeycomb extrusion die 1 is constructed in such a manner that
intersecting slits 2 are arranged on its front surface by using a
plurality of cell blocks 3 and raw material feeding holes 4
communicated with the slits 2 at its intersecting portion are
arranged on its back surface. A batch to be formed is supplied
through the raw material feeding holes 4 arranged on its back
surface into the die 1, and a honeycomb formed body is extruded
from the slits 2 arranged on its front surface. A feature of the
honeycomb extrusion die 1 according to the invention is that, as
shown in FIG. 3, respective cell blocks 3 comprises a die base
metal 11, an electrolytic plating layer 14 arranged on the die base
metal 11, a TiN layer 12 arranged on the electrolytic plating layer
14 by means of CVD, and a TiCN layer 13 arranged on the TiN layer
12 by means of CVD. In the case that the TiCN layer 13 is arranged
directly on the electrolytic plating layer 14, the TiN layer 12 is
not arranged in FIG. 3.
[0026] Hereinafter, an actual experiment will be explained.
[0027] Experiment
[0028] As the die base metal, use was made of martensite stainless
steel. The slits and the raw material feeding holes were formed to
the die base metal by performing ECM process and/or wheel grinding
process. Moreover, R portion (formed by electrolytic process)
having a round portion was arranged to corners of surfaces of
respective die base metals to which the slit was formed. Then, with
respect to the die base metal, electrolytic plating process using a
material shown in the following Table 2 was performed, and a
plating layer having a thickness shown in Table 2 was formed on a
die surface. Conditions of electrolytic plating process were pH:
not more than 1.5, bath temperature: room temperature and current
density: 5-20 A/dm.sup.2 in the case of wood-strike bath and were
pH: 3-5, bath temperature: 20-70.degree. C. and current density:
2-20 A/dm.sup.2 in the case of sulfamic acid bath, and the
experiment was performed according to the plating methods shown in
Table 2. Moreover, electrolytic plating conditions of Co were bath
temperature: room temperature and current density: 2-20 A/dm.sup.2,
and electrolytic plating conditions of Cu were bath temperature:
20-50.degree. C. and current density: 1-15 A/dm.sup.2. After that,
the single TiCN layer or the TiN layer and the TiCN layer in this
order with a thickness shown in Table 2 was (were) formed as shown
in Table 2 at a temperature of 700-850.degree. C. by means of CVD.
In the case of forming the TiN layer and the TiCN layer, a
thickness was calculated by their sum. In this manner, the die
according to the example of the present invention was manufactured.
Moreover, a die according to a comparative example, in which the
electrolytic plating layer was not arranged, was also manufactured
as shown in Table 2. With respect to the dies according to the
example of the present invention and the comparative example,
whether the chipping was generated or not and positions at which
the chipping was generated were observed. The results were shown in
Table 2.
2 TABLE 2 Plating Plating thickness Film thickness Die base metal
material Plating method (.mu.m) Film kinds (.mu.m) Chipping state
Examples of Martensite Ni Wood-strike bath 0.1 TiN + TiCN 10 No
Chipping present stainless steel invention Martensite Ni
Wood-strike bath 0.1 TiN + TiCN 20 No Chipping stainless steel
Martensite Ni Wood-strike bath 0.1 TiN + TiCN 30 No Chipping
stainless steel Martensite Ni Wood-strike + 1 TiN + TiCN 25 No
Chipping stainless steel sulfamic acid bath Martensite Ni
Wood-strike + 3 TiN + TiCN 25 No Chipping stainless steel sulfamic
acid bath Martensite Ni Wood-strike + 8 TiN + TiCN 25 No Chipping
stainless steel sulfamic acid bath Martensite Ni Wood-strike bath
0.1 TiCN 15 No Chipping stainless steel Martensite Ni Wood-strike
bath 0.1 TiCN 22 No Chipping stainless steel Martensite Co Bath
using CoCl.sub.2 1 TiN + TiCN 20 No Chipping stainless steel
solution Martensite Cu Bath using CuSO.sub.4 1 TiN + TiCN 20 No
Chipping stainless steel solution Comparative Martensite No plating
No plating -- TiN + TiCN 15 Chipping (R portion) examples stainless
steel Martensite No plating No plating -- TiN + TiCN 23 Chippings
(R portion stainless steel and edge portion)
[0029] As clearly understood from the results shown in Table 2, in
the example of the present invention, the chipping was not
generated, but, in the comparative example, the chipping was
generated particularly at the R portions. For reference, a cross
sectional photograph after forming the film according to the
example of the present invention (die base metal+electrolytic Ni
layer+TiN layer+TiCN layer) was shown in FIG. 4, and a cross
sectional photograph after forming the film according to the
comparative example (die base metal+TiN layer) was shown in FIG. 5.
In both cases, a die cut-out cross section was polished and the
etched, and then the cross section was observed by the scanning
electron microscope (SEM). If the example of the present invention
shown in FIG. 4 and the comparative example shown in FIG. 5 are
compared, it is understood that, in the example of the present
invention shown in FIG. 4, respective layers are contacted
strongly, but, in the comparative example shown in FIG. 5, a
corroded portion between the die base metal and the TiN layer is
shown by black and a failure connection is generated between them.
Moreover, FIG. 6 shows a chipping state after forming the film in
the comparative example having a film thickness of 15 .mu.m.
[0030] As clearly understood from the above explanations, according
to the invention, since the electrolytic plating layer is arranged
between the die base metal and the TiCN layer or between the die
base metal and the TiN layer, a contact property therebetween can
be improved, so that the chipping is not easily generated if a
thickness of the film is thicker. Moreover, since the plating layer
is made of the metal and the metal has an excellent stiffness, it
is possible to reduce a heat stress between the die base metal and
the TiCN layer or the TiN layer, and thus the chipping is not
easily generated. Further, since an impurity in the electrolytic
plating layer is very little, it is possible to obtain normal TiCN
particles.
* * * * *